Paddle leads for neurostimulation and method of delivering the same

ABSTRACT

Paddle lead including a lead body having a distal end, a proximal end, and a central axis extending therebetween. The lead body includes opposite first and second sides that extend between the distal and proximal ends. The paddle lead also includes electrodes disposed along the first side of the lead body that are configured to apply neurostimulation therapy within an epidural space of a patient. The electrodes are electrically coupled to conductive pathways that extend through the proximal end of the lead body. The lead body includes a flexible material a flexible material that is configured to flex when a fluid pressure is imposed on the lead body in the epidural space. The lead body is configured to have a non-planar contour that folds or curves about the central axis when experiencing the fluid pressure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of Ser. No. 16/565,178, filed 9 Sep.2019, which is a continuation of U.S. application Ser. No. 14/198,260,filed 5 Mar. 2014 (now abandoned), which claims benefit to U.S.Application No. 61/791,288, filed on 15 Mar. 2013 (now expired), thesubject matter of each are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

One or more embodiments of the subject matter described herein generallyrelate to systems having paddle leads for generating electric fieldsproximate to nerve tissue.

BACKGROUND

Neurostimulation systems (NS) are devices that generate electricalpulses and deliver the pulses to nerve tissue to treat a variety ofdisorders. Spinal cord stimulation (SCS) is a common type ofneurostimulation. In SCS, electrical pulses are delivered to nervetissue in the spine typically for the purpose of chronic pain control.While a precise understanding of the interaction between the appliedelectrical energy and the nerve tissue is not fully appreciated, it isknown that application of an electric field to spinal nerve tissue caneffectively mask or alleviate certain types of pain transmitted fromregions of the body associated with the stimulated nerve tissue.

NS and SCS systems generally include a pulse generator and one or moreleads electrically coupled to the pulse generator. A lead includes anelongated body of insulative material. A stimulating end portion of thelead includes multiple electrodes that are electrically coupled to thepulse generator through wire conductors. The stimulating end portion ofa lead is implanted proximate to nerve tissue (e.g., within epiduralspace of a spinal cord) to deliver the electrical pulses. A proximal endof the lead body includes multiple terminal contacts, which are alsoelectrically coupled to the wire conductors. The terminal contacts, inturn, are electrically coupled to the pulse generator. The terminalcontacts receive electrical pulses from the pulse generator that arethen delivered to the electrodes through the wire conductors to generatethe electric fields. The pulse generator is typically implanted withinthe individual and may be programmed (and re-programmed) to provide theelectrical pulses in accordance with a designated sequence.

Typically, one of two types of leads is used. The first type is apercutaneous lead, which has a rod-like shape and includes electrodesspaced apart from each other along a single axis. The second type oflead is a laminectomy or laminotomy lead (hereinafter referred to as a“paddle” lead). A paddle lead has an elongated planar body with a thinrectangular shape (i.e., paddle-like). Although the paddle lead mayinclude only one row or column of electrodes, the paddle lead typicallyincludes an array of electrodes that are spaced apart from each otheralong a substantially common plane. The number of electrodes may be, forexample, two, four, eight, or sixteen. Due to their dimensions andphysical characteristics, conventional paddle leads require a surgicalprocedure (a partial laminectomy) to implant the lead. The lead istypically positioned within the epidural space adjacent to the dura ofthe spinal cord.

However, conventional paddle leads include a rigid, substantiallyinflexible body. In some cases, the dimensions of the epidural space andthe dimensions of the paddle lead result in the paddle lead pressingagainst the spinal cord. If the compression is substantial, it may causeunwanted consequences, such as a tingling sensation, pain, partialparalysis, or even complete paralysis of the legs.

Therefore, a need remains for implantable paddle leads that do notcompress the nerves of the spinal cord or compress the nerves less thanknown paddle leads.

BRIEF SUMMARY

In accordance with an embodiment, a neurostimulating paddle lead isprovided that includes a lead body having a distal end, a proximal end,and a central axis extending therebetween. The lead body includesopposite first and second sides that extend between the distal andproximal ends. The paddle lead also includes electrodes disposed alongthe first side of the lead body that are configured to applyneurostimulation therapy within an epidural space of a patient. Theelectrodes are electrically coupled to conductive pathways that extendthrough the proximal end of the lead body. The lead body includes aflexible material a flexible material that is configured to flex when afluid pressure is imposed on the lead body in the epidural space. Thelead body is configured to have a non-planar contour that folds orcurves about the central axis.

The lead body may have longitudinal edges that join the first and secondsides. The longitudinal edges may extend generally along the centralaxis. The longitudinal edges may close around a dura membrane whenexperiencing the fluid pressure. For example, the lead body may beconfigured to flex such that the longitudinal edges move closer to eachother within the epidural space. As another example, the central axismay extend along a geometric center of a cross-section of the lead bodythat is transverse to the central axis. In some embodiments, thelongitudinal edges and the central axis do not exist within a commonplane when the leady body is in the epidural space.

In some embodiments, the lead body is configured to flex within theepidural space when the fluid pressure is at least 15 cmH₂0. In someembodiments, the lead body is configured to flex within the epiduralwhen the fluid pressure is at least 5 cmH₂0.

The paddle lead may also include a tool receptacle that is coupled tothe lead body along the second side. The tool receptacle may have areceptacle cavity that opens along the second side or the proximal end.In some instances, the lead body and the tool receptacle may beintegrally formed, such as through a common molding process.

In another embodiment, a lead-delivery assembly is provided thatincludes a paddle lead having a distal end, a proximal end, and acentral axis extending therebetween. The paddle lead includes oppositefirst and second sides that extend between the distal and proximal ends.The paddle lead includes electrodes that are disposed along the firstside of the paddle lead and that are configured to applyneurostimulation therapy within an epidural space of a patient. Thelead-delivery assembly also includes a tool receptacle that is coupledto the paddle lead. The tool receptacle may have a receptacle cavitythat opens along the second side or along the proximal end. Thelead-delivery assembly may also include a delivery tool having a leadingend. The leading end is sized and shaped for insertion into thereceptacle cavity.

In some embodiments, the tool receptacle is integrally formed with thepaddle lead. In some aspects, the cavity is a lumina having an openingalong the second side. The lumina may extend from the opening toward thedistal end.

The tool receptacle may include a pocket having the cavity. The cavityof the pocket may have a width that is greater than half of a width ofthe lead body. The delivery tool may have a leading edge with a greatestdimension that extends along the width of the cavity when the deliverytool is disposed within the cavity.

In another embodiment, a lead-delivery assembly is provided thatincludes a paddle lead having a distal end, a proximal end, and acentral axis extending therebetween. The paddle lead includes oppositefirst and second sides that extend between the distal and proximal ends.The paddle lead includes electrodes that are disposed along the firstside of the paddle lead and are configured to apply neurostimulationtherapy within an epidural space of a patient. The lead-deliveryassembly includes an insert tray configured to removably hold the paddlelead. The insert tray has a planar body with an open-sided recess thatis dimensioned to hold the paddle lead. The lead-delivery assembly alsoincludes a delivery tool having a leading end. The leading end isconfigured to engage the insert tray to position the paddle lead withinthe epidural space. In some aspects, the insert tray may have a distalshroud that is configured to surround the distal end of the paddle lead.

In another embodiment, a method of locating a paddle lead in an epiduralspace of a patient is provided. The method includes inserting a deliverytool into a tool receptacle of a paddle lead. The paddle lead hasopposite first and second sides that extend between distal and proximalends of the paddle lead. The paddle lead includes electrodes that aredisposed along the first side. The tool receptacle is disposed along thesecond side. The method also includes directing the paddle lead into anepidural space of a patient and to a designated location in the epiduralspace and removing the delivery tool from the tool receptacle.

In some aspects, the tool receptacle is integrally formed with thepaddle lead. The cavity may be a lumina having an opening along thesecond side. The lumina may extend from the opening toward the distalend. The tool receptacle includes a pocket having the cavity. The cavityof the pocket has a width that is greater than half of a width of thelead body. The delivery tool has a leading edge with a greatestdimension that extends along the width of the cavity when the deliverytool is disposed within the cavity.

In another embodiment, a method of locating a paddle lead in an epiduralspace of a patient is provided. The method includes positioning a paddlelead on an insert tray that is configured to removably hold the paddlelead. The insert tray has a planar body with an open-sided recess thatis dimensioned to hold the paddle lead. The method also includesdirecting the insert tray into an epidural space of a patient and to adesignated location in the epidural space and removing the insert trayfrom the paddle lead.

The insert tray may include a distal shroud that is configured tosurround the distal end of the paddle lead. In some embodiments,directing the insert tray into the epidural space includes using adelivery tool to direct the insert tray.

While multiple embodiments are disclosed, still other embodiments of thedescribed subject matter will become apparent to those skilled in theart from the following Detailed Description, which shows and describesillustrative embodiments of disclosed inventive subject matter. As willbe realized, the inventive subject matter is capable of modifications invarious aspects, all without departing from the spirit and scope of thedescribed subject matter. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and notrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of one embodiment of a neurostimulating (NS)system in accordance with one embodiment.

FIG. 2 is a plan view of a paddle lead formed in accordance with oneembodiment that may be used with the NS system of FIG. 1 .

FIG. 3 is a cross-section of the paddle lead of FIG. 2 taken along theline 3-3 in FIG. 2 .

FIG. 4 is an isolated view of a paddle lead formed in accordance withone embodiment that may be used with the NS system of FIG. 1 .

FIG. 5 is a cross-section of the paddle lead of FIG. 4 taken along theline 5-5 in FIG. 4 .

FIG. 6 is a view of a paddle lead formed in accordance with oneembodiment located within an epidural space of a spinal canal of apatient.

FIG. 7 is a cross-section of a paddle lead formed in accordance with oneembodiment that is configured to flex about a central axis whenexperiencing a fluid pressure from a dura membrane.

FIG. 8 is another cross-section of a paddle lead formed in accordancewith one embodiment that is configured to flex about a central axis whenexperiencing a fluid pressure from a dura membrane.

FIG. 9 is another cross-section of a paddle lead formed in accordancewith one embodiment that is configured to flex about a central axis whenexperiencing a fluid pressure from a dura membrane.

FIG. 10 is an isolated view of a paddle lead having a tool receptacleformed in accordance with one embodiment.

FIG. 11 is a cross-section of the paddle lead of FIG. 1O having adelivery tool located within a receptacle cavity of the paddle lead.

FIG. 12 is a perspective view of a paddle lead having a tool receptacleformed in accordance with one embodiment.

FIG. 13 is a cross-section of the paddle lead of FIG. 12 having adelivery tool located within a receptacle cavity of the paddle lead.

FIG. 14 is a perspective view of a paddle lead having a tool receptacleformed in accordance with one embodiment.

FIG. 15 is a cross-section of the paddle lead of FIG. 14 .

FIG. 16 is another cross-section of the paddle lead of Figure

FIG. 17 is a perspective view of an insert tray formed in accordancewith one embodiment that is configured to receive a paddle lead.

FIG. 18 is a plan view of the insert tray of FIG. 17 holding the paddlelead.

DETAILED DESCRIPTION

Embodiments described herein include paddle leads that are capable ofconforming in shape after the paddle lead is inserted into the epiduralspace. For example, the paddle lead may be configured to flex or bowalong the width and/or length when a fluid pressure in the dura isimposed on the lead body in the epidural space. In some cases, theflexible paddle lead may prevent or reduce pressure along the spinalnerves. FIG. 1 depicts a neurostimulation (NS) system 100 that generateselectrical pulses for application to tissue, such as spinal cord tissue,of a patient according to one embodiment. For embodiments that stimulatespinal cord tissue, the nerve tissue may include dorsal column (DC)fibers and/or dorsal root (DR) fibers. The NS system 100 includes an NSdevice (or pulse generator) 150 that is adapted to generate electricalpulses in order to apply electric fields to the tissue. The NS device150 is typically implantable within an individual (e.g., patient) and,as such, may be referred to as an implantable pulse generator (IPG). Theimplantable NS device 150 typically comprises a housing that encloses acontroller 151, a pulse generating circuitry 152, a charging coil 153, abattery 154, a far-field and/or near field communication circuitry 155,a battery charging circuitry 156, a switching circuitry 157, etc. of thedevice. The controller 151 typically includes a processor or otherlogic-based device for controlling the various other components of theNS device 150. Software code is typically stored in memory of the NSdevice 150 for execution by the processor to control the variouscomponents of the device.

The NS device 150 may comprise a separate or an attached extensioncomponent 170. If the extension component 170 is a separate component,the extension component 170 may connect with the “header” portion of theNS device 150 as is known in the art. If the extension component 170 isintegrated with the NS device 150, internal electrical connections maybe made through respective conductive components. Within the NS device150, electrical pulses are generated by the pulse generating circuitry152 and are provided to the switching circuitry 157. The switchingcircuitry 157 connects to outputs of the NS device 150. Electricalconnectors (e.g., “Bal-Seal” connectors) within a connector portion 171of the extension component 170 or within the header may be employed toconduct the electrical pulses. Terminal contacts (not shown) of one ormore neurostimulator leads 110 are inserted within the connector portion171 or within the header for electrical connection with respectiveconnectors. Thereby, the pulses originating from NS device 150 areprovided to the neurostimulator lead 110. The pulses are then conductedthrough wire conductors of the lead 110 and applied to tissue of anindividual via electrodes 111. In the illustrated embodiment, theneurostimulator lead is a lead configured for insertion after a laminectomy or a laminotomy. The lead is hereinafter referred to as a“paddle lead.”

For implementation of the components within NS device 150, a processorand associated charge control circuitry for an implantable pulsegenerator is described in U.S. Patent Publication No. 20060259098,entitled “SYSTEMS AND METHODS FOR USE IN PULSE GENERATION,” which isincorporated herein by reference. Circuitry for recharging arechargeable battery of an implantable pulse generator using inductivecoupling and external charging circuits are described in U.S. patentSer. No. 11/109,114, entitled “IMPLANTABLE DEVICE AND SYSTEM FORWIRELESS COMMUNICATION,” which is incorporated herein by reference. Oneor more NS device and one or more paddle leads that may be used withembodiments described herein are described in U.S. Patent ApplicationPublication No. US 2013/0006341.

An example and discussion of “constant current” pulse generatingcircuitry is provided in U.S. Patent Publication No. 20060170486entitled “PULSE GENERATOR HAVING AN EFFICIENT FRACTIONAL VOLTAGECONVERTER AND METHOD OF USE,” which is incorporated herein by reference.One or multiple sets of such circuitry may be provided within the NSdevice 150. Different pulses on different electrodes may be generatedusing a single set of pulse generating circuitry using consecutivelygenerated pulses according to a “multi-stimset program.” Complex pulseparameters may be employed such as those described in U.S. Pat. No.7,228, 179, entitled “Method and apparatus for providing complex tissuestimulation patterns,” and International Patent Publication Number WO2001/093953 A1, entitled “NEUROMODULATION THERAPY SYSTEM,” which areincorporated herein by reference. Alternatively, multiple sets of suchcircuitry may be employed to provide pulse patterns that includesimultaneously generated and delivered stimulation pulses throughvarious electrodes of one or more stimulation leads as is also known inthe art. Various sets of parameters may define the pulse characteristicsand pulse timing for the pulses applied to various electrodes as isknown in the art. Although constant current pulse generating circuitryis contemplated for some embodiments, any other suitable type of pulsegenerating circuitry may be employed such as constant voltage pulsegenerating circuitry.

FIGS. 2 and 3 illustrate a plan view and a cross-section, respectively,of a paddle lead 200 formed in accordance with one embodiment. Thepaddle lead 200 includes a lead body 202 having a distal end 204 (FIG. 2), a proximal end 206 (FIG. 2 ), and a central axis 208 extendingtherebetween. As shown in FIG. 3 , the central axis 208 extendsgenerally along a geometric center of a cross-section of the paddle lead200.

During an implantation procedure, the distal end 204 is typically theleading end that is inserted through an incision and into the spinalcolumn. As shown, a cable or tube 210 extends from the proximal end 206.The cable 210 may include conductive pathways (e.g., wire conductors)that extend from the lead body 202 to an NS device or pulse generator(not shown), such as the NS device 150 (FIG. 1 ). The lead body 202 alsoincludes opposite first and second sides 212 and 214 that extend betweenthe distal and proximal ends 204, 206.

The paddle lead 200 also includes longitudinal edges 218, 220 thatextend along a length (e.g., a greatest dimension) of the lead body 202.The longitudinal edges 218, 220 may extend generally along or parallelto the central axis 208. As shown in FIG. 3 , the longitudinal edges218, 220 may also join the first and second sides 212, 214.

The paddle lead 200 may be characterized as having a central portion 215that includes the central axis 208 and extends between the first andsecond sides 212, 214 and first and second wing portions 217, 219. Thefirst and second wing portions 217, 219 are joined by the centralportion 215 and extend to the longitudinal edges 218, 220, respectively.

The lead body 202 has a length L1 that extends along the central axis208 between the distal and proximal ends 204, 206, a width W1 thatextends transverse to the central axis 208 between the longitudinaledges 218, 220, and a thickness T1 that extends between the first andsecond sides 212, 214. Although the thickness T1 is shown as beingsubstantially uniform, in other embodiments, the thickness T1 may vary.For example, the central portion 215 may have a greater thickness thanthe wing portions 217, 219. For some portions of the lead body 202, thethickness T1 may change abruptly or more gradually as the thickness T1extends along the width W1 or along the length L1. For instance, thethickness T1 may reduce or taper as the wing portion 217, 219 approachthe longitudinal edges 218, 220.

The paddle lead 200 also includes a plurality of electrodes 216 that aredisposed along the first side 212 and are configured to provide aneurostimulation therapy in an epidural space of a patient. For example,electrical pulses transmitted from the pulse generator may be providedat a predetermined schedule or frequency to provide an effective therapyfor the patient. The second side 214, when the paddle lead is disposedin the epidural space, may interface with an anatomical structure (e.g.,bone, ligament, or other portions of the spine). As described herein,the paddle lead 200 may be configured to change or conform the contourof the lead body 202.

FIGS. 4 and 5 illustrate an isolated view and a cross-section,respectively, of a paddle lead 230 formed in accordance with oneembodiment. The paddle lead 230 includes a lead body 232 having a distalend 234 (FIG. 2 ), a proximal end 236 (FIG. 2 ), and a central axis 238extending therebetween. As shown in FIG. 5 , the central axis 238extends generally along a geometric center of a cross-section of thepaddle lead 230.

Like the paddle lead 200 (FIG. 2 ), the paddle lead 230 includes a cableor tube 240 that extends from the proximal end 236. The cable 240includes conductive pathways (e.g., wires) that extend from the leadbody 232 to a pulse generator (not shown). The lead body 232 alsoincludes opposite first and second sides 242 and 244 that extend betweenthe distal and proximal ends 234, 236. The paddle lead 230 also includeslongitudinal edges 248, 250 that extend along a length (e.g., a greatestdimension) of the lead body 232. The longitudinal edges 248, 250 mayextend generally along or parallel to the central axis 238. As shown inFIG. 5 , the longitudinal edges 248, 250 may also join the first andsecond sides 242, 244.

The paddle lead 230 also includes a plurality of electrodes 246 that aredisposed along the first side 242 and are configured to provideneurostimulation therapy in an epidural space of a patient. In theillustrated embodiment, the electrodes 246 form an array that includes a5×4 grid of electrodes 246 in which the electrodes 246 are substantiallyevenly distributed along the central axis 238. In alternativeembodiments, the electrodes 246 may form a single row or column thatextends along the central axis 238 and are spaced apart from each other.The second side 244, when the paddle lead is disposed in the epiduralspace, may interface with an anatomical structure (e.g., bone, ligament,or other portions of the spinal column. Although not indicated, the leadbody 232 may have a central portion and first and second wing portionslike the lead body 202. Of course, the lead body 232 also has a length,width, and thickness.

In particular embodiments, the characteristics of the materials used toform the lead bodies 202, 232 and/or the dimensions (e.g., thickness) ofthe lead bodies 202, 232 permit the lead bodies 202, 232 to be readilyflexible or conformable (e.g., supple) when a designated amount of fluidpressure provided through the dura is experienced. The lead body 202,232 may include one or more biocompatible materials. The materials maybe electrically insulating (e.g., dielectric materials). Non-limitingexamples of such materials include polyimide, polyetheretherketone(PEEK), polyethylene terephthalate (PET) film (also known as polyesteror Mylar), polytetrafluoroethylene (PTFE) (e.g., Teflon), or parylenecoating, polyether bloc amides, polyurethane. In some embodiments, thematerial of the lead body that surrounds the metal components (e.g.,electrodes and the wire conductors that couple to the electrodes)consists essentially of at least one of polyimide, polyetheretherketone(PEEK), polyethylene terephthalate (PET) film, polytetrafluoroethylene(PTFE), parylene, polyether bloc amides, or polyurethane.

In certain embodiments, the dimensions of the lead bodies 202, 232 areconfigured such that the lead bodies 202, 232 are flexible when a fluidpressure is imposed on the lead body in the epidural space. For example,the thickness for one or more portions of the lead body may not exceed adesignated amount and/or the thickness for one or more designatedportions of the lead body may be reduced to allow flexing. The leadbodies may also be characterized as being malleable, supple,conformable, and/or moldable.

By way of example, the fluid pressure imposed in the epidural space maybe between about 5 to about 20 cmH20 (or about 4 to about 15 mmHg).Thus, embodiments may be configured to flex within the epidural spacewhen the fluid pressure in the spinal canal is above at least 5 cmH20, 6cmH20, 7 cmH20, 8 cmH20, 9 cm H20, 10 cmH20, 11 cmH20, 12 cmH20, 13cmH20, 14 cmH20, 15 cmH20, 16 cm H20, 17 cm H20, 18 cm H20, 19 cmH20, or20 cm H20. In some embodiments, the lead body is configured to flexwithin the epidural space when the fluid pressure is at least 5 cmH20.In particular embodiments, the lead body is configured to flex withinthe epidural space when the fluid pressure is at least 10 cmH20 or, moreparticularly, at least 15 cmH20.

In some cases, one or more portions of the lead body may include morerigid structures or stiffeners. For example, the longitudinal edges mayinclude a more rigid dielectric material that extends along thelongitudinal edges for at least a portion of the length. The distal endmay also include portions that have a more rigid material.

When the lead body of a paddle lead is flexed or shaped between the duraand another anatomical structure (e.g., ligamentum flavum), the shape ofthe lead body may change the effective arrangement of the electrodeswith respect to each other. In some embodiments, the pattern orarrangement of the electrodes may be configured or re-arranged based onthe operative shape of the lead body (or ranges of shapes that the leadbody may change between). More specifically, the arrangement ofelectrodes may be customized for each patient. In some embodiments, thearrangement of electrodes may be based, at least in part, on dataobtained regarding an anatomical configuration of a target location forthe paddle lead (e.g., the location where the lead will be operating toprovide neurostimulation). For example, the data may include images ofthe location where the paddle lead will be implanted. Accordingly, atleast some of the arrays or patterns of electrodes may be irregular. Forinstance, one row (or column) of electrodes may have differentseparation distances between adjacent electrodes and an adjacent row (orcolumn) may also have different separation distances between adjacentelectrodes. The patterns for each of the rows (or columns) may bedifferent.

As one example of differently patterned rows or columns, a first row orcolumn may have five electrodes in which the first and second electrodesare separated by X, the second and third electrodes are separated by1.05X, the third and fourth electrodes are separated by 0.95X, and thefourth and fifth electrodes are separated by 0.85X. A second row orcolumn may have five electrodes in which the first and second electrodesare separated by Y, the second and third electrodes are separated by0.85Y, the third and fourth electrodes are separated by 0.95Y, and thefourth and fifth electrodes are separated by Y. In some embodiments, Ymay equal X.

FIG. 6 is a view of a paddle lead 300 that is located within an epiduralspace 302 of a spinal canal 304 of a patient. For reference, the duramembrane 306, the spinal cord 308, and the vertebra 305 are also shown.The paddle lead 300 may be similar or identical to the paddle leads 200and 230 described with respect to FIGS. 2 and 3 , respectively. Otherpaddle leads may also be used as set forth herein. FIG. 6 providesenlarged views in which the paddle lead has a pre-loaded shape orcondition 310 and a loaded shape or condition 312. The pre-loaded shape310 may be the shape of the paddle lead 300 before the fluid pressure isimposed on the paddle lead 300 in the epidural space 302.

The loaded shape 312 may be the shape of the paddle lead 300 when thepaddle lead is operatively positioned at a designated location in theepidural space 302 and the fluid pressure causes the paddle lead tochange shape. The fluid pressure is indicated by the arrows P in theenlarged views. In the loaded shape 312, the fluid pressure P, thedimensions of the epidural space 302 defined by various anatomicalstructures, and the dimensions and malleability of the paddle lead 300may determine the configuration of the paddle lead 300 in the loadedshape 312. For example, the paddle lead 300 may conform to theanatomical structures in the surrounding environment, such as thevertebra 305, dura membrane 306, or other structures (e.g., ligaments,fat). In FIG. 6 , the shape of the paddle lead 300 is primarilydetermined by the dura membrane 306.

FIGS. 7-9 illustrate cross-sections of the paddle lead 300 and, inparticular, the different loaded shapes that the paddle lead 300 mayhave in the epidural space 302. In FIGS. 7-9 , the paddle lead 300 is atleast partially pressed against the vertebra 305. However, depending onthe anatomical structures in the spinal canal of a patient, the paddlelead 300 may also engage other structures, such as the dura membrane.

With respect to FIG. 7 , the paddle lead 300 includes a lead body 314with a central portion 316 and wing portions 318, 320. The wing portions318, 320 include longitudinal edges 319, 321 of the lead body 314. Thelead body 314 also includes an electrode side (or first side) 324 and aposterior side (or second side) 326. The electrode side 324 faces thedura membrane 306, and the posterior side 326 faces the vertebra 305. Insome cases, the electrode side 324 may directly engage the dura membrane306 and/or the posterior side 326 may directly engage the vertebra 305.

A central axis 322 of the paddle lead 300 is indicated and extendsthrough the central portion 316. The central axis 322 extends into andout of the page. The central axis 322 may extend through a geometriccenter of the cross-section from the proximal end (not shown) to adistal end (not shown) of the lead body 314. Depending on the dimensionsof the lead body 314, the central axis 314 may not be perfectly linear.Furthermore, when the paddle lead 300 is in the loaded shape 312, thecentral axis 322 may not be linear.

As described herein, the paddle lead 300 (or the lead body 314)comprises a flexible material that is configured to flex when a fluidpressure is imposed on the paddle lead 300 in the epidural space 302.The paddle lead 300 is configured to adjust its shape from thepre-loaded shape 310 (FIG. 6 ) to the loaded-shape 312 shown in FIGS.7-9 . The loaded-shape 312 may be a non-planar contour in which the leadbody 314 is folded or curved about the central axis 322. The non-planarcontour may be based on the fluid pressure, the dimensions of theepidural space 302, and the dimensions and composition of the paddlelead 300.

FIGS. 7-9 illustrate different non-planar contours of the paddle lead300 in which the lead body 314 is folded or curved about the centralaxis 322. It should be noted that FIGS. 7-9 are for illustrativepurposes only to demonstrate how the paddle lead 300 permits the fluidpressure within the spinal canal to change a shape of the paddle lead300. For example, in FIG. 7 , the lead body 314 has a substantiallyuniform radius of curvature along the electrode side 324. In FIG. 8 ,the lead body 314 has a smaller radius of curvature proximate to thecentral portion 316 of the lead body 314 and a greater radius ofcurvature (or more planar shape) along the wing portions 318, 320.

In some embodiments, the central axis 322 may be located proximate to anapex of the loaded lead body 314 as shown in FIGS. 7 and 8 . In otherembodiments, however, the apex may be located between the central axis322 and the longitudinal edge 319. FIG. 9 illustrates thisconfiguration. The configuration shown in FIG. 9 may occur due to theshape of an anatomical structure, such as the vertebra 305.

The longitudinal edges 319, 321 extend generally along the central axis322. As shown in FIGS. 7-9 , the longitudinal edges 319, 321 partiallyclose around the dura membrane 306 when the fluid pressure is imposed.In some embodiments, the lead body 314 is configured to flex such thatthe longitudinal edges 319, 321 move closer to each other within theepidural space 302. More specifically, the width of the lead body 314 inthe pre-loaded shape is greater than the width of the lead body 314 inthe loaded shape. In some embodiments, the lead body 314 is configuredsuch that the longitudinal edges 319, 321 and the central axis 322 maynot exist within a common plane X when the lead body 314 is in theepidural space 302 and the fluid pressure is imposed. For example, asshown in FIG. 9 , a plane that extends through the longitudinal edges319-321 does not include the central axis 322.

FIGS. 10-18 illustrate different mechanisms or methods of delivering apaddle lead to the epidural space. In one or more embodiments, a paddlelead may be configured to be transported from the incision sight andinto the epidural space using a delivery tool. Collectively, the paddlelead and the delivery tool may be referred to as a lead-deliveryassembly. The delivery tool may direct the paddle lead to a designatedlocation. In some cases, the delivery tool directly engages the paddlelead. For example, the paddle lead may be formed to include a toolreceptacle that receives the delivery tool. In other cases, the deliverytool may directly engage another component that is coupled to the paddlelead, such as an insert tray or shroud. The other component may beseparate and distinct from the paddle lead. For example, the deliverytool and the other component may be configured to be removed from thebody.

FIGS. 10-16 illustrate embodiments in which the paddle lead includes atool receptacle that receives the delivery tool. For example, FIGS. 1Oand 11 show an isolated view and a cross-section, respectively, of apaddle lead 400. The paddle lead 400 may be similar to the paddle leads110, 200, 230, and 300 described above. The paddle lead 400 includes anelectrode side 402 (FIG. 11 ) and a posterior side 404. As shown, theposterior side 404 may include a tool receptacle 406 along the posteriorside 404. The tool receptacle 406 may comprise a layer of dielectricmaterial that is coupled to and extends along the posterior side 404.The layer of dielectric material may be formed with the paddle lead 400.As such, the tool receptacle 406 may remain with the paddle lead 400after the paddle lead 400 is positioned in the epidural space. In otherembodiments, the tool receptacle 406 may be removed from the paddle lead400.

As shown, the tool receptacle 406 includes a receptacle cavity 408 thatis accessed through the posterior side 404 or through a proximal edge410 (FIG. 10 ) of the paddle lead 400. In the illustrated embodiment,the receptacle cavity 408 has a cavity opening 412 that opens along theposterior side 404. In particular embodiments, the receptacle cavity 408may be a lumina that extends lengthwise from the cavity opening 412 to adistal end 414 of the paddle lead 400.

The receptacle cavity 408 and the cavity opening 412 are configured toreceive a delivery tool 416 (FIG. 11 ). The delivery tool 416 may be anelongated object that is sized and shaped to be inserted through thecavity opening 412 and advanced toward the distal end 414. By way ofexample, the delivery tool 416 may be a stylet, guidewire, or otherelongated object. In some cases, the delivery tool 416 is capable ofchanging its rigidity. When the delivery tool 416 is inserted into thetool receptacle 406, a leading end of the delivery tool 416 may engagean interior surface and thereby move (e.g., direct) the paddle lead 400.Once the paddle lead 400 is located in the designated location, thedelivery tool 416 may be removed.

FIG. 12 is a perspective view of a paddle lead 420 having a toolreceptacle 422 formed in accordance with one embodiment, and FIG. 13 isa cross-section of the paddle lead 420. In the illustrated embodiment,the tool receptacle 422 is a pocket or shroud having a receptacle cavity424. The receptacle cavity 424 is accessed along a posterior side 426 ofthe paddle lead 420. In some embodiments, the pocket 422 and/or thereceptacle cavity 424 has a width W2 (FIG. 13 ) that is configured toextend along a substantial portion of a width W3 of the paddle lead 420.For example, the width W2 may be greater than half of a width W3 of thepaddle lead 420. In such embodiments, a delivery tool 426 may also havea width W4 that is substantially equal to the width W2 (e.g., greaterthan half of the width W3 of the paddle lead 420). More specifically,the delivery tool 426 may have an end portion 428 that extendstransverse to the central axis of the paddle lead when the delivery tool426 is located within the receptacle cavity 424. The end portion 428 ofthe delivery tool 426 may be spatula-shaped and have a leading edge 430.The leading edge 430 may have the width W4. As such, the delivery tool426 may provide structural integrity to the paddle lead 420 as thepaddle lead 420 is directed into the epidural space. In other words, thedelivery tool 426 may function as a stiffening element when the deliverytool 426 is within the pocket 422.

FIG. 14 is a perspective view of a paddle lead 440 having a toolreceptacle 442 formed in accordance with one embodiment. FIGS. 15 and 16are cross-sections of the paddle lead 440 taken along the lines 15-15and 16-16, respectively. The tool receptacle 442 may be similar to thetool receptacle 422 (FIG. 12 ) and may be referred to as a pocket orshroud. In the illustrated embodiment, the tool receptacle 442 is formedwith the lead body of the paddle lead 440. In alternative embodiments,the tool receptacle 442 may be a separate component. For example, thealternative tool receptacle 442 may be like a sleeve that is configuredto be removed from the paddle lead 440.

As shown, the tool receptacle 442 includes a receptacle cavity 444 thatis configured to receive an end portion 446 of a delivery tool 448. Thereceptacle cavity 444 is open-sided as shown in FIGS. 14 and 16 for amajority of a length of the paddle lead 440. However, the toolreceptacle 442 may have a pocket end 450 that receives a distal end ofthe delivery tool 448. The delivery tool 448 may be dimensioned toextend across a majority or an entirety of a width of the receptaclecavity 444.

FIG. 17 is an isolated perspective view of an insert tray 460, and FIG.18 is a plan view of the insert tray 460 holding a paddle lead 462. Theinsert tray 460 has an open-sided recess 464 that is sized and shaped toreceive the paddle lead 462. The insert tray 460 may have a distal end466 that includes a lip 468. The lip 468 may protect a distal end 470 ofthe paddle lead 462 to facilitate the insertion process. The lip 468 mayalso prevent inadvertent sliding of the paddle lead 462 in the insertiondirection. During the insertion process, a delivery tool 472 may engagea portion of the insert tray 460 to direct the insert tray 460 into thebody. For example, the delivery tool 472 may have a clip that grips aproximal end 474 of the insert tray 460.

It is to be understood that the subject matter described herein is notlimited in its application to the details of construction and thearrangement of components set forth in the description herein orillustrated in the drawings hereof. The subject matter described hereinis capable of other embodiments and of being practiced or of beingcarried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items.

Unless specified or limited otherwise, the terms “mounted,” “connected,”“supported,” and “coupled” and variations thereof are used broadly andencompass both direct and indirect mountings, connections, supports, andcouplings. Further, “connected” and “coupled” are not restricted tophysical or mechanical connections or couplings. Also, it is to beunderstood that phraseology and terminology used herein with referenceto device or element orientation (such as, for example, terms like“central,” “upper,” “lower,” “front,” “rear,” “distal,” “proximal,” andthe like) are only used to simplify description of one or moreembodiments described herein, and do not alone indicate or imply thatthe device or element referred to must have a particular orientation. Inaddition, terms such as “outer” and “inner” are used herein for purposesof description and are not intended to indicate or imply relativeimportance or significance.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentlydescribed subject matter without departing from its scope. While thedimensions, types of materials and coatings described herein areintended to define the parameters of the disclosed subject matter, theyare by no means limiting and are exemplary embodiments. Many otherembodiments will be apparent to those of skill in the art upon reviewingthe above description. The scope of the inventive subject matter should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written in means -plus-function format and are not intended to be interpreted based on 35U.S.C. § 112, sixth paragraph, unless and until such claim limitationsexpressly use the phrase “means for” followed by a statement of functionvoid of further structure.

Although the invention has been described with reference to certainembodiments, persons skilled in the art will recognize that changes maybe made in form and detail without departing from the spirit and scopeof the invention.

The following claims recite aspects of certain embodiments of theinventive subject matter and are considered to be part of the abovedisclosure.

What is claimed:
 1. A method of locating a paddle lead in an epiduralspace of a patient, the method comprising: inserting a delivery toolinto a tool receptacle of a paddle lead, the lead body elongated betweena distal end and a proximal end, a central axis extending along a lengthof the lead body, the lead body including opposite first and secondsides that extend between the distal and proximal ends, the lead bodyincluding longitudinal edges that extend along the length of the leadbody in a common direction as the central axis; wherein the lead bodycomprises a flexible material that is configured to flex when a fluidpressure in the epidural space is imposed on the second side of the leadbody by the spinal fluid, the lead body configured to form a non-planarcontour that folds or curves about the central axis to maintain thefirst side against the dural membrane in response to the fluid pressureimposed on the second side, wherein the lead body is to flex and conformto the dural membrane when the second side of the lead body experiencesa designated amount of the fluid pressure between 5 cm H20 and 20 cmH2O; electrodes disposed along the first side of the lead body andconfigured to apply a neurostimulation therapy within an epidural spaceof a patient, the electrodes being electrically coupled to conductivepathways that extend through the proximal end of the lead body, whereinthe first side is configured to engage a dural membrane and the secondside is configured to be exposed to spinal fluid; an edge structureprovided along the longitudinal edges of the lead body, the edgestructure made of a material that is more rigid that the flexiblematerial forming the lead body, wherein the edge structure includes arigid dielectric material that extends along the longitudinal edges forat least a portion of the length, the dielectric material toelectrically insulate the electrodes along the edges of the lead bodywhen applying neurostimulation therapy; directing the paddle lead to adesignated location in an epidural space of a patient at which the firstside of the lead body is maintained against the dural membrane inresponse to the fluid pressure imposed on the second side; and removingthe delivery tool from the tool receptacle.
 2. The method of claim 1,further comprising forming the edge structure with a rigid dielectricmaterial that extends along the longitudinal edges for at least aportion of the length.
 3. The method of claim 1, wherein the distal endincludes an end structure made of a material that is more rigid that theflexible material forming the lead body.
 4. The method of claim 1,wherein, as an operative shape of the lead body changes during thedirecting, an effective arrangement of the electrodes changes withrespect to each other.
 5. The method of claim 4, further comprising,prior to the inserting, reconfiguring or re-arranging at least one of apattern or arrangement of the electrodes based on the operative shapethat the lead body is expected to form.
 6. The method of claim 1,further comprising arranging at least some of an array or pattern of theelectrodes irregularly, such that at least one row or column of theelectrodes has different separation distances between adjacentelectrodes and at least one of adjacent rows or columns have differentseparation distances between the adjacent electrodes.
 7. The method ofclaim 1, further comprising providing the lead body with a width thatextends transverse to the central axis between the longitudinal edges,the lead body further including a thickness that extends between thefirst and second sides, the thickness varying such that the centralportion has a greater thickness relative to a thickness of at least oneof the first and second wing portions.
 8. The method of claim 7, whereinthe thickness varies gradually as the thickness extends along at leastone of the width or length.
 9. The method of claim 7, wherein thethickness reduces or tapers as the first and second wing portionsapproach the corresponding longitudinal edges.
 10. The method of claim1, wherein the first and second sides represent an electrode side and aposterior side, respectively, the method further comprising providing atool receptacle in the posterior side of the central portion, the toolreceptacle configured to receive a tool, the tool receptacle extendingthe length of the lead body proximate to at least one of the first andsecond wing portions or the central portion.
 11. The method of claim 10,further comprising providing a layer of dielectric material proximatethe tool receptacle, the layer of dielectric material extending alongthe posterior side, the layer of dielectric material formed with thelead body such that the tool receptacle remains with the lead body afterthe paddle lead is positioned in the epidural space.
 12. The method ofclaim 1, further comprising forming the edge structure of anon-biodegradable material.